Production of a polymer composition

Abstract

PCT No. PCT/GB96/00305 Sec. 371 Date Jan. 6, 1998 Sec. 102(e) Date Jan. 6, 1998 PCT Filed Feb. 12, 1996 PCT Pub. No. WO96/25452 PCT Pub. Date Aug. 22, 1996A process of making a polyhydroxyalkanoate PHA latex comprises making a liquid-form solution of such PHA in a water soluble liquid and contacting that solution with water under shear. Suitably the solution is prepared at a temperature between the boiling point of water and 10 DEG C. below the melting point of the PHA as measured by DSC for example by melt separating PHA from a microbiological suspension thereof, dissolving it in the water soluble liquid, and then contacting the solution at over 100 DEG C. with water at 50 DEG -95 DEG C. The water-soluble liquid may be for example 1,2-propandiol or a liquid more volatile than water such as ethanol, propanol or tertiary butanol. A surfactant may be present or added after contacting, for example one providing steric stabilisation such as an acrylic graft copolymer emulsifier.

What is claimed is: 
     
       1. A process of making a PHA latex which comprises making a liquid-form solution of such PHA in a water soluble liquid and contacting that solution with water under shear. 
     
     
       2. A process according to claim 1 in which comprises making the solution at a temperature between the boiling point of water and 10° C. below the melting point of the PHA as measured by DSC. 
     
     
       3. A process according to claim 1 which comprises melt separating PHA from a microbiological suspension thereof. 
     
     
       4. A process according to claim 1 which comprises contacting the PHA solution at over 100° C. with water at 50°-95° C. 
     
     
       5. A process according to claim 1 which includes the step of filtering the PHA solution before contacting it with water. 
     
     
       6. A process according to claim 1 in which the water-soluble liquid is 1,2-propandiol. 
     
     
       7. A process according to claim 1 in which the liquid is more volatile than water. 
     
     
       8. Process according to claim 7 in which the liquid is selected from the class consisting of ethanol, propanols and tertiary butanol. 
     
     
       9. A process according to claim 1 in which the contacting is effected in absence of surfactant but surfactant is added after contacting. 
     
     
       10. A process according to claim 9 which includes use of surfactant providing steric stabilisation. 
     
     
       11. A process according to claim 10 in which the surfactant is an acrylic graft copolymer emulsifier. 
     
     
       12. A process according to claim 1 in which the PHA comprises repeating units of formula --O--C m  H n  --CO-- where m is 3 or 4, there are units with m=3 and m=4 copolymerised together with respectively a C 1  and C 2  side chain on the carbon next to oxygen in the chain and the content of m=3 units is at least 70 mol %.